Lubricating oils thickened with pteridine derivatives



United States 1 1" he present invention relates to'novel lubricant greases and to the method of preparing same. More 'pa'rticularly,

; it 're'latestonovel greases coniprising a lubricant vehicle thickened with certain high-melting-pteridine derivatives. Greases of this type, particularly those wherein the lubricant vehicle comprises a silicone polymer oil, have demonstrated exceptional stability at elevated temperatures.

As-lubricants are required-to perform athigher and higher temperatures because of increased speeds of engines and machines, the advent of jet propulsion, atomic energy as a source of power, etc.,it-has become increasingly difficult to prepare greases fulfilling-the requirements of such lubricants. -'In attempting to provide such greases, theart has progressed from theuse of-petr'oleumlubricant vehi- --eles thiekened with'metal soaps oflong chain fatty acids,

e.-g.-liLhium 'hydr'oxyste'arate, to more thermally stable synthetic lubricating oils such as the aliphaticdiesters of dicarboxylic acids, silicone polymers, -etc., thickenedwith such soaps or inorganic materials such as silica gels. The progress of thickener research has not in general, however, kept pace with the development of lubricant vehicles. And at temperatures as high as 400 to 450 F. or higher, there are few if any greases available which will retain their consistency and lubricity "for any substantialperiod of time. 7

In recent years various synthetic lubricant vehicles, e. g. the silicones, fluorocarbons, etc., have been found to be potentially valuable for use in greases "e'mployed at very high temperatures because of their thermal stability and relatively low volatility. Unless, however, a thickener having substantially the same degree of thermal stability is available to produce a grease from such an oil, they are of little use. 7

It is a primary object of the present invention to provide lubricant greases which are stable at elevated temperatures.

Afurther object is to provide a'readily producible series of greases'embodying a novel class of thickening agents capable of yielding lubricants particularly suitable for use at temperatures as high as about 450 F. or more. A particular object of the present invention is to provide greases which are efiective lubricants at temperatures as high as about 450 F. for substantial periods'of time. These and additional objects will beapparent from the following detailed description.

"We have found that the aboveobje'cts'can be attained "with a grease composition'comprising'ahigh boilingjior "rnally liquid lubricant vehicle and fromabout'5%' toabout 70%, and preferably from about 10% 'to about 50 %,'of a pteridine derivative having the general formula in which Z is selected from the group consisting of OH atent '0 a aim-NH, radicals, R and R are substituents 'sel'ec'ted'from the group consisting of H,OH, alkyl,

and

2-amino-4-hydroXy-6,7-(2,2 biphenylene)-pteridine 2-amino-4-hydroxy-6,7-diphenyl pteridine 2-aminoe4-hydroxy-efl-di-'(3=n-itrophenyl) pteridine' V '2-amino-4-hydroxy, 6,7-di-(2-chlorophenyl)-pteridine 'wh'ilethe pteridine derivatives ofthe above type are all efieetive'thickeners for the preparation of high temperat'ure greases,-it is not to be implied thatalls'erve' with'idem -tical efficiency, since the specific "aeti-vityof'the "various "compoundsmay vary to some extent depending upon'the nature and severity of theservic'e to"which th'e'y are' 'subjected.

The described pteridine derivative'skanbe prepared in accordance with the procedure describedby Cain'et'al. in the Journal of the American ChemicalSo'ci'e'tyfvol. -68, p.

1996 (1 946). Briefly, the reaction can beillustrat'ed by 2,415-triamiiio' ti-hydroxypyrimidine bisulfite whereR and R'are as above defined.

In "place of the 2,4,5-triamino-6-hydroxy Ipyrimidine bisulfite, the corresponding sulfate can be'e'mployed.

Briefly; the preparation of the herein descfibed' pteridine derivative thickeners can be carried out asfollows:

A saturated solution of the pyrimidine'bisulfite or sulfate in dimethyl sulfoxide, or other suitable -s'olveht is prepared; and to the saturated solution isadded th'e diketohe,"or a mixture of diketones, inapproxiinately equal molar amounts (1 mole of the dilt'etone to 1 moleof the pyrimidine bisulfite or sulfate). The mixture is then heated, withor without stirring, to -125 C. and held 'at this temperature for about 5 hours to carry the reaction to completion. As the reaction approaches completion, s'omeprecipitation occurs. -At the end'of the '5 hourreac- :ti'onperiod, the reaction mass isp'oured into alarg'e excess fbf water, the reaction product precipitated and then filtered. The filtered precipitate is then washed with a,

. nitrobenzene, etc.

.asaass v dry pteridine derivative with the desired amount of the lubricant vehicle, it is preferred to use the moist washed pteridine derivative. In this case, the moist material is mixed with the lubricant vehicle, the acetone or other wash liquid removed by evaporation or distillation, and the resulting paste then milled as on a three-roll mill.

Oleaginous lubricant vehicles which can be thickened with the herein described pteridine derivative to form greases of the present invention, can be silicone polymer oils, mineral lubricating oils, synthetic hydrocarbon lubricating oils, synthetic lubricating oils such as polyalkylene glycols and their derivatives, high molecular weight esters of dicarboxylic acids, polyfiuoro derivatives of organic compounds such as the trifiuorovinyl chloride polymers known as Fluorolube (made by Hooker Chemical Company) and the trifiuorochloroethylene polymers, known as Kel-F-40" (made by The M. W. Kellogg Company), and other lubricant vehicles.

The silicone polymer oils which may be employed in accordance with the present invention are those falling substantially within the lubricating; oil viscosity range. In general, such oils have the following unit structure:

R [la] it-..

' such oils as have a viscosity at 100 F. of from about '100 S. S. U. to about 1250 S. S. U. Such products are generally colorless and inert, have a very low volatility and undergo relatively slight change in viscosity for a given change in temperature. Relatively common oils of this type are dimethylsilicone polymer, phenylmethylsilicone polymer, chlorophenylmethylsilicone polymer, etc., it being preferred to employ either the phenylmethyl silicone or the chlorophenylmethylsilicone polymer in accordance herewith. Methods of preparing such compounds are taught in numerous patents, e. g. U. S. 2,410,346, U. S. 2,456,496, and in the literature suchas Chemistry of the Silicones, by Rochow, page 61 et seq. A particularly desirable phenylmethylsilicone polymer for use in accordance with the present invention is Dow- Corning 550 Silicone Fluid, a product of Dow-Corning, Inc., which has a Saybolt Universal viscosity at 100 F. of about 300 to about 400 seconds. Another suitable silicone polymer is a chlorophenylmethylsilicone marketed as GE 81406 by General Electric Company. 1

.Other oleaginous vehicles which may be employed herewith are, for example, mineral oils in the lubricating oil viscosity range, i. e. from about 50 S. S. -U. at 100 F. to

about 300 S. S. U. at.210 .The se mineral oils are preferably solvent extracted, to substantially remove the low V. I. constituents, e. g. aromatics, with phenol, furfural, B,B'-dichloro diethylether(Chlor ex), liquid S Synthetic lubricating oils resulting range such as high molecular weight polyoxyalkylene compounds such as polyalkylene glycols and esters thereof, aliphatic diesters of dicarboxylic acids such as the butyl, hexyl, 2-ethylhexyl, decyl, lauryl, etc. esters of sebacic acid, adipic acid, azeleic acid, etc., may be thickened by the pteridine compounds of the present invention to produce excellent greases. Polyfiuoroderivatives of organic compounds, particularly hydrocarbons, and dibasic acid esters of H(CF -),,CH OH, in the lubricating oil viscosity range can be thickened with compounds of the present invention. Other synthetic oils, such as esters of aliphatic carboxylic acids and polyhydric alcohol, e. g. trimethylolpropane pelargonate and pentaerythritol hexanoate, can be used as suitable oil vehicles. 'Where the grease product is to be employed under high temperature conditions lubricating oils which are stable, i. e. do not decompose, at the temperatures to be encountered should be used as the lubricant vehicle. For such uses, it is preferredto use oils such as thesilicone polymers,,the diesters of dicarboxylic acids, and the like.

The preparation of the herein described grease is illustrated by the following examples:

EXAMPLE I To a saturated solution consisting of 5 grams 2,4,5- triamino fi-hydroxypyrimidine sulfate in 100 ml. of dimethyl sulfoxide, one mole of benzil was added for each mole of the pyrimidine sulfate and the mixture heated at 120-l25 C. for about 5 hours to carry the reaction to completion. At the end of this time, the reaction mass was poured into a large excess of water to precipitate the reaction product, 2-amino-4-hydroxy-6,7-diphenyl pteridine. The precipitated product was then filtered and washed with acetone to remove the water and dimethyl sulfoxide. The moist acetone-washed precipitated peteridine compound was then mixed with sufiicient DC-SSO Silicone Fluid to give a grease produce having 23% of the thickener, the acetone evaporated from the 'mixture and the resultant paste milled to form the grease.

EXAMPLE II To a saturated solution consisting of 5 grams 2,4,5- triamino-fi-hydroxy pyrimidine sulfate in 100 ml. of dimethyl sulfoxide, one mole of nitrobenzil was added for each mole of the pyrimidine sulfate and the mixture heated at 120-125" C. for about 5 hours to carry the reaction to completion. At the end of this time, the

. reaction mass was poured into a large excess of water to precipitate the reaction product, 2-amino-4-hydroxy-6,7- di-(3-nitrophenyl)-pteridine. The precipitated product was then filtered and washed with acetone to remove the water and dimethyl sulfoxide.

precipitated pteridine compound was then mixed with Themoist acetone-washed DC-550 Silicone Fluid to give a product having 22% of the thickener, the acetone evaporated from the mixture and the resultant paste milled to form the grease.

EXAMPLE III water to precipitate thereaction product, 2-amino-4-hydr'oxy 6,7-di 2-chlorophenyl l pteri dine.

from polymerization of unsaturatedhydrocarbons orother;

The precipitated product was then filtered and washed with acetone to remove the water and dimethyl sulfoxide. The moist acetone-washed precipitated pteridine compound was then mixed with DC-550 Silicone Fluid to give a grease product having 25% of the thickener, the acetone evaporated from the mixture and the resultant paste milled to form the grease.

In place of the 2,4,5-triamino-6-hydroxypyrimidine 5. s'ulf ate used in the. above examples, the 2,4;-triamino-6- hydroxy pyrimidine bisulfite can be used.

In Table I are set forth ASTM penetration data obtainedton, grease compositionsof the above examples.

1 Values convertedfromXstze cone penetration values.

In Table II are tabulated high temperature hearing test data on a grease composition formulated with DC-550 (supra) and 2-amino-4-hydroxy-6,7-di-(chlorophenyl) pteridine. The bearing test is one tentatively adopted by the Coordinating Research Council, referred to as the ABEC-NLGI Test, and described in ABEC-NLGI Technical Bulletin No. 5, November 1944. The test is carried out as follows: three grams of the grease sample are placed in each of two bearings disposed on a test spindle. One bearing, a special heat treated precision 204 Norma-Hoffman bearing, is subjected to a temperature of 450 F. in an oven, while the second bearing, a standard New Departure 204 bearing is at much lower temperature. Temperatures are determined by a thermocouple inserted in the grease between the races of the bearing in the oven. Failure is adjudged to occur when (1) the temperature of the test bearing reaches 470 F. or higher, (2) wattage in excess of 300% of normal wattage is required, or (3) the bearing does not turn over at the beginning of a test cycle (the test is conducted in cycles of 20 hours operating and 4 hours at rest).

The grease products of the present invention can con tain one or more Well known addition agents, stable under the existing conditions of use, to impart various desired properties thereo, such as, by way of example, antioxidants, extreme pressure agents, corrosion inhibitors, anti-leak agents, anti-foam agents, graphite, molybdenum sulfide, etc.

Percentages given herein and in the appended claims are weight percentages, unless otherwise stated.

Although the present invention has been described with reference to specific preferred embodiments thereof, the invention is not limited thereto, but includes within its scope such modifications and variations as come within the scope and spirit of the appended claims.

We claim:

1. A lubricant grease comprising a normally liquid lubricant vehicle thickened with from about 5% to about 70% of a pteridine derivative having the general formula in which 2 is selected from the group consisting of OH and NH: radicals, R and R are substituents selected from the group consisting of H, OH, alkyl,

asaaa and in which R" are substituents selected from the group consisting of hydrogen, alkyl, nitro, and halogen groups.

2. A lubricant grease as described in claim 1 in which the pteridine derivative is 2-amino-4,6,7-trihydroxy pteridine.

3. A lubricant grease as described in claim 1 in which the pteridine derivative is 2,4,6,7-tetrahydroxy pteridine.

4. A lubricant grease as described in claim 1 in which the pteridine derivative is 2-amino-4-hydroxy-6,7-diphenyl pteridine.

5. A lubricant grease as described in claim 1 in which the pteridine derivative is 2-amino-4-hydroxy-6,7-di-(3- nitrophenyl) pteridine.

6. A lubricant grease as described in claim 1 in which the pteridine derivative is 2-amino-4-hydroxy-6,7-di-(2- chlorophenyl) pteridine.

7. A lubricant grease as described in claim 1 in which the lubricant vehicle is a silicone polymer oil.

8. A lubricant grease as described in claim 1 in which the lubricant vehicle is a hydrocarbon lubricating oil.

9. A lubricant grease as described in claim 1 in which the lubricant vehicle is a diester of a dicarboxylic acid.

10. A lubricant grease comprising a major proportion of a silicone polymer oil in the lubricating oil viscosity range and from about 10% to about 50% of 2-amino-4- hydroxy-6,7-diphenyl pteridine.

11. A lubricant grease comprising a major proportion of a silicone polymer oil in the lubricating oil viscosity range and from about 10% to about 50% of 2-amino-4- hydroxy-6,7-di-(3-nitrophenyl) pteridine.

12. A lubricant grease comprising a major proportion of a silicone polymer oil in the lubricating oil viscosity range and from about 10% to about 50% of 2-amino-4-hydroxy- 6,7-di-(2-chlorophenyl) pteridine.

13. In the method of preparing a stable high temperature grease comprising a normally liquid lubricant vehicle thickened with a pteridine derivative having the general formula in which Z is selected from the group consisting of OH and NH radicals, R and R are substituents selected from the group consisting of H, OH, alkyl,

and I wherein R and R are as herein defined precipitating the resultant reaction product by the addition of a large excess of water, filtering the precipitate'and washingthe filtered precipitate with an organic solvent, the improvement coml5 prisingaddi'ng the normally liquid lubricant vehicle prior to removing said organic solvent, subsequently removing -the organic-'solvent from said mixture, and then milling the resultant paste.

14. The method of claim 13 in which the lubricant vehi- '10 "cle is '5 siliconeiiolymer oil and the organic solvent is acetone.

in which R" are substituentsselected from the group consisting of hydrogen, alkyl, nitro, and halogen groups, wherein said pteridine derivative is prepared by reacting 2,4,5-triamino-6-hydroxypyrimidine sulfate with a diketone having the general formula i Q References (filed in the tile of this patent I PTATE$ PAT NT 2,710,840 Swakon et al. lune 14, 1955 ll- 2,740,7s4 Sletiinger et 51;"; Apr. 3, 1956- a 7 2,791,586 Sletzinger et al. May7, 1957 

1. A LUBRICANT GREASE COMPRISING A NORMALLY LIQUID LUBRICANT VEHICLE THICKENED WITH FROM ABOUT 5% TO ABOUT 70% OF A PTERIDINE DERIVATIVE HAVING THE GENERAL FORMULA 